Impact of adherence to the Mediterranean diet on stroke risk

Abstract

Stroke is a leading cause of morbidity and mortality worldwide, and dietary patterns have emerged as a significant modifiable factor in stroke prevention. The Mediterranean diet, characterized by high intake of fruits, vegetables, whole grains, nuts, olive oil, and fish, has been widely recognized for its cardiovascular benefits. However, its specific impact on stroke risk requires further elucidation. We conducted a comprehensive meta-analysis of 30 studies, including both cohort and case-control designs, to evaluate the relationship between adherence to the Mediterranean diet and the risk of stroke. A systematic search was performed across multiple databases, and a random-effects model was used to estimate pooled hazard ratios (HRs) with 95% confidence intervals (CIs). Heterogeneity was assessed using the I² statistic, and publication bias was examined through funnel plots and Egger's regression test. Additionally, trial sequential analysis was conducted to determine the adequacy of the sample size. The meta-analysis revealed a significant reduction in stroke risk among individuals adhering to the Mediterranean diet, with a pooled HR of 0.88 (95% CI: 0.84-0.91). Notably, a significant heterogeneity was detected (I² = 34%). The Z-score plot from trial sequential analysis confirmed that the sample sizes were sufficient to draw definitive conclusions. However, a potential publication bias was identified. The case-control studies confirmed a highly significant effect (HR = 0.54, 95% CI: 0.4-0.73). The funnel plots in both settings hinted at the presence of a potential publication bias, supported by a significant Egger's test. Our findings provide robust evidence supporting the protective effect of the Mediterranean diet against stroke. Despite the presence of some heterogeneity and potential publication bias, the cumulative evidence suggests that promoting the Mediterranean diet could serve as an effective public health strategy for stroke prevention. Further research is recommended to explore the underlying mechanisms and to assess the diet's impact across diverse populations.

Keywords: Case–control; Diet; Dietary intervention; Meta-analysis; Stroke prevention.

Fig. 1

Flow diagram illustrating the article selection process

Fig. 2

Results for all cohort studies comparing Mediterranean diet and stroke risk. There is a highly significant reduction in stroke incidence with a total HR of 0.88 (A). On the other hand, the funnel plot indicates a potential publication bias (B). The Z-score plot of cohort studies investigating the correlation indicates that no additional studies are needed to get a definitive conclusion (C). SE, standard error; CI, confidence interval; IV, inverse variance; APIS, a priori information size; AIS, actual information size; RRR, relative risk ratio

Fig. 3

Case–control studies comparing Mediterranean diet and the risk of stroke. The forest plots show a highly marked effect with a HR of 0.54 (A). The funnel plot indicates a potential publication bias (B). Z-score plot of case–control studies investigating the correlation between obesity and colorectal cancer indicates the necessity of further studies to establish a definitive conclusion (C). SE, standard error; CI, confidence interval; IV, inverse variance; APIS, a priori information size; AIS, actual information size; RRR, relative risk ratio